For one hot minute, it looked like Justin Timberlake would be Jailbird Timberlake after his voting booth selfie was totally not 'NSync with Tennessee state law.

Yep, Mr 'Sexy Back' himself copped a bit of heat when he posted an Instagram shot while voting in his hometown of Memphis.

"Hey! You! Yeah, YOU! I just flew from LA to Memphis to #rockthevote!!!" the 35-year-old wrote. "No excuses, my good people! There could be early voting in your town too. If not, November 8th! Choose to have a voice! If you don't, then we can't HEAR YOU! Get out and VOTE! #excerciseyourrighttovote."

There was no problem with him encouraging his 37 million followers to vote for the next president of the United States.

However, in Tennessee, taking photos or videos inside polling locations are criminal offences, with penalties of up to 30 days in prison and a (GASP!) $50 fine.

A representative from Shelby County, Tennessee District Attorney's office earlier told TMZ that Justin's actions were "under review" – but that was a "mistake", according to the just-released official statements.

"While we are aware of an allegation that someone may have violated a Tennessee state election law, we have not been presented anything by an investigative authority," Vince Higgins, communications director for Shelby County District Attorney General, told the Commercial Appeal.

Shelby County District Attorney General Amy Weirich said in a statement to KVVU: "The statement released earlier today by my office regarding Justin Timberlake and an investigation was incorrect and was released without my knowledge.

"I am out of town at a conference. No-one in our office is currently investigating this matter nor will we be using our limited resources to do so."

Justin now lives in California, and recently bought a home in Nashville. He decided to cast an early vote at the New Bethel Missionary Baptist Church in Germantown.

The Tennessee Secretary of State's office took the opportunity to throw a LOL-worthy Timberlake pun in their statement.

"We're thrilled Justin can't stop the feeling when it comes to voting so much that he voted early in person and is promoting voting to his millions of fans," said spokesman Adam Ghassemi.

He added that voters will be asked to put their phones away at the booths. Say 'Bye, Bye, Bye' to your iPhones, voters.

Back in August, Justin and his wife Jessica Biel, 34, hosted a $44k-per-head fundraiser for Democrat presidential nominee Hillary Clinton.